Hi, Fred,
There's plenty to talk about!
On Jul 24, 2006, at 9:05 PM, Fred Sturm wrote:
> It's something I've been pondering quite a while. There are a
> number of approaches to the top of the hammer crown. Steinway's is
> to file with rough paper - no finer than 120, maybe just 100.
> Leaves a "forgiving" surface, "easier to mate."
If you're referring to the amount of cushion at the strike available
to obscure mating (as you definitely do, two paragraphs later), that
cushion is considerably reduced by any reinforcing at the crown.
> Just one more observation along these lines: if you are pressing the
> hammer to the string, it is possible to vary the pressure through a
> pretty wide range........
and of course if one is really ham-fisted, there's no such thing as
an open string.
> (assuming you have close letoff - I prefer the finger under the
> jack technique rather than the cloth on the rep lever, pressing the
> keys, as I think you can get a more sensitive reading).
a necessary assumption
> Varying the pressure and using a piece of music wire to pluck, you
> can get a finer sense of the precision of your mating work.
Backing one's finger off from the kind of pressure that erases open
strings, the differences in hammer contact begin to appear.
Continuing to lessen pressure widens those differences, producing as
you say "a finer sense of the precision of your mating work". (And I
do like plucking with my used-to-be-a-bass-string hook. First, in the
mid-treble section, it fits nicely between the front of the dampers
and the capo. Second, as soon as I've decided it's the string that
needs correcting, the hook is already down there.
> On the other extreme is Kawai, using 1000 to 1500 paper to finish
> the crown. My sense is that Kawai's final action on the crown (with
> extra fine paper) does the equivalent of the Yamaha technique of
> pounding the hammer against the strings (which are muted): it packs
> the felt as much as it remove fiber. Very little fiber comes off
> using those 1500 paddles (some, but not much).
I've always imagined the grit on a file combing rather than cutting,
even though its combing action can certainly remove felt (especially
down at 80 grit). But this action does depend on the relationship
between the size of the bits of grit, and the diameter of felt fibers.
I'm guessing that somewhere at around 180 grit, the "bits" (more
specifically that portion of them which stick out from the adhesive
layer) no longer go in the felt mass more than one fiber deep. At
this point, the chance is far greater that instead of reaching in and
uprooting handfuls of fibers, they'll only be aligning (combing)
fibers in the top layer. Most of my work is NY Steinway hammers, but
I rarely use anything finer than 320 grit. It seems to me that above
that the bits are easily less "tall in their profile" than the fibers
they are being asked to comb (and quickly approaching only 1/2 or 1/3
the fiber diameters). What are the fibers getting at this point, a
massage, a tickle? For that matter, what does the alignment of fibers
accomplish towards a properly balanced wave-form on he string, if
that alignment is only one fiber deep?
This would also seem to me to be independent of whether we're talking
soft ("airhead") hammers or hard-pressed dense hammer. Something like
400 or 600 (not to mention 1500) is only working on the outer-most
layer of felt, quite literally one fiber thick.
> What is really happening is that the "trough" is made round again
> (the trough at the tip is created by the "blooming" of the felt in
> response to needling, something that doesn't happen with NY
> Steinway hammers).
I'm not clear what you're describing here. Is the "trough" the string
groove? I've heard about the " 'blooming' of the felt in response to
needling". Cauliflowering, the texture of a hundred mosquito bites.
It's a function of hard pressed hammers.
> But what I wonder is whether the "forgiving" mating of the rougher
> sanded hammer is really forgiving in the long run. Or have you just
> set yourself up for problems in the future, when packing of felt
> caused by playing reveals the less precise mating job, that was
> covered up by fuzz. This might be one reason why people complain
> about their NY Steinway voicing jobs not lasting.
I can't speak to this, except to say that someone who gets seduced by
a "forgiving" (rather, "accepting" or absorbing) surface, into
underestimating the actual amount of mating, will pay for it. In the
same way that open strings disguised by hard pressure on a soft crown
will appear as soon as you back off the pressure (see above), a
hammer blow with such inattentive mating will sound reasonable at the
force levels which erase the open strings. However, just as with soft
crown mating, open string whines will quickly show up at the quiet
end of the dynamic range where the hammer blow isn't strong enough to
erase the open strings. Probably what's not lasting is the "soft
voicing". And someone who doesn't notice this probably doesn't notice
other stuff.
Which bring up another point: theoretically as soon as the crown gets
string cuts, there's no such thing as open strings. The string cuts
may be of different lengths, but ironically, these grooves are the
product of another kind of mating.
Well yeah, that's for worn hammers. The importance of proper mating
on freshly filed hammers is clear to the ear. But still, how about
those worn hammers (that is, as long as they don't stray at all in
their spacing).
Sure love those mental magnifying glasses.........!
mr bill
wbps at vermontel.net
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